BY JUSTIN RAY

October 9, 2000 -- Follow the countdown and launch of the Pegasus rocket with NASA's HETE 2 spacecraft. Reload this page for the very latest on the mission.

MONDAY, OCTOBER 9, 2000
0730 GMT (3:30 a.m. EDT)

An international space endeavor to search for mysterious gamma ray bursts in the furthest reaches of the universe got underway smoothly today with the launch of NASA's High Energy Transient Explorer 2 by an Orbital Sciences Pegasus rocket.

The HETE 2 spacecraft was delivered into its planned orbit ranging from 406 miles to 396 miles and inclined 1.9 degrees to either side of Earth's equator. Verification of the satellite's initial health is expected after a few hours in space.

It is the start of a four-year mission to detect the cosmos' most powerful explosions since the Big Bang that first created the universe. The craft is designed to accurate locate the bursts, which last anywhere from milliseconds to a few minutes, and provide alerts to astronomers on Earth for further investigation. HETE 2 has a dozen ground stations along the equator to receive the alerts.

"Routinely, HETE 2 will provide astronomers with a good chance of seeing a burst while it is still going on," said George Ricker, senior research scientist at MIT and principal investigator for the mission.

Gamma ray bursts are possibly caused by two black holes coming together, or an incredible star explosion called a hypernova. The bursts produce gamma radiation that is invisible to the human eye. "It's still a mystery what causes these things. We hope to shed some light on that," said Daniel Reichart, a California Institute of Technology astronomer. "Beyond that, this mission is probably going to discover things that we can't possibly predict."

The 273-pound satellite was built by Massachusetts Institute of Technology for NASA. Other partners include the Los Alamos National Laboratory, France's Centre National d'Etudes Spatiales (CNES) and Centre d'Etude Spatiale des Rayonnements (CESR) and Japan's Institute of Physical and Chemical Research (RIKEN). The science team also includes members from the University of California (Berkley and Santa Cruz) and the University of Chicago.

HETE 2 carries three instruments, and is a replacement the original HETE that was lost in a launch mishap of a Pegasus rocket nearly four years ago when the booster failed to release the satellite.

Today's launch originated from the Kwajalien Missile Range located in the Marshall Islands of the Central Pacific Ocean. It marked the first time a satellite has been orbited from the site made famous for testing ballistic missile weaponary for the U.S. military.

The Orbital Sciences L-1011 carrier aircraft took off at 0440 GMT from the Kwajalein Atoll and followed a pre-planned, 58-minute flight that culminated with release of the three-stage, air-launched Pegasus vehicle at 0538 GMT while flying on a southeasterly track. The flight azimuth was 118.5 degrees.

Just over 11 minutes later, HETE 2 was released into a slightly elliptical orbit, completing the Pegasus rocket's 30th flight in its 10-year history.

"From my prospective, it is exactly the countdown you want. No problems. All the assets were green all throughout, weather was great, the rocket was in great shape, so it was a perfect countdown," NASA Launch Manager Ray Lugo said afterwards. "From the time the rocket ignited all the through spacecraft separation, everything was very nominal. And I think we got a very nominal orbit for the spacecraft."

This marked the first use of Pegasus' sixth different launch site, something no other rocket in the world matches. Orbital has conducted the previous launches from Edwards Air Force Base and Vandenberg Air Force Base in California, Cape Canaveral in Florida, Wallops Flight Facility in Virginia and Gran Canaria of the Canary Islands off Africa.

Today's launch occurred over 4,200 miles from the U.S. mainland but was actually controlled from Hangar AE at Cape Canaveral Air Force Station in Florida. It was NASA's first attempt at using a remote launch control center and all appeared to go as planned, including the highly complex network of multiple ground stations and four orbiting satellites to relay vehicle telemetry, voice communications and video from the L-1011 aircraft flying 39,000 feet above the Central Pacific, and later the soaring rocket, back to Cape Canaveral.

0551 GMT (1:51 a.m. EDT)

Orbital Sciences officials report the all indications show a successful launch today of the $15 million Pegasus rocket with NASA's $8.4 million HETE 2 spacecraft. The satellite was delivered into a 590 by 650 km orbit inclined 1.95 degrees to the equator according to data from the rocket's guidance computer.

Check back a little later for a complete wrap-up story on today's launch.

0549 GMT (1:49 a.m. EDT)

T+plus 11 minutes. SPACECRAFT SEPARATION! NASA's High Energy Transient Explorer 2 satellite has been deployed from the Orbital Sciences Pegasus rocket's third stage to complete today's launch.

0548 GMT (1:48 a.m. EDT)

T+plus 10 minutes. Pegasus has arrived in orbit as the third stage burns out, officials report. Coming up on payload deployment in just over a minute.

0547 GMT (1:47 a.m. EDT)

T+plus 9 minutes. The second stage has been jettisoned and the third stage motor is now firing, accelerating the HETE 2 spacecraft to its orbit.

0546 GMT (1:46 a.m. EDT)

T+plus 8 minutes. Pegasus is performing a reorientation maneuver using its cold-gas thrusters to achieve the proper position for separation of the second stage.

0544 GMT (1:44 a.m. EDT)

T+plus 6 minutes. Everything going well so far with today's launch. No problems have been reported. Data coming back from the Pegasus rocket all reported normal.

0543 GMT (1:43 a.m. EDT)

T+plus 5 minutes. The Pegasus rocket's onboard computer has determined the coast period will last to 527 seconds based upon the performance of the vehicle's first two stages. Also, the projected orbit is 319 by 353 nautical miles inclined 1.948 degrees to the equator.

0541 GMT (1:41 a.m. EDT)

T+plus 3 minutes. The second stage has burned out as planned. The Pegasus rocket is now in a ballistic coast period for the next six minutes or so.

0540 GMT (1:40 a.m. EDT)

T+plus 2 minute, 20 seconds. The payload fairing has been jettisoned. Second stage continues to burn.

0540 GMT (1:40 a.m. EDT)

T+plus 1 minute, 45 seconds. Officials confirm separation of the spent first stage and second stage ignition.

0539 GMT (1:39 a.m. EDT)

T+plus 1 minute, 25 seconds. The first stage has burned out. Standing by for staging.

0539 GMT (1:39 a.m. EDT)

T+plus 40 seconds. The Pegasus rocket is passing through maximum dynamic pressure. Attitude of the vehicle is reported normal.

0538 GMT (1:38 a.m. EDT)

IGNITION. First stage ignition of the Orbital Sciences Pegasus rocket launching NASA's High Energy Transient Explorer 2 spacecraft to seek out the most powerful explosions in the universe.

0538:20 GMT (1:38:20 a.m. EDT)

DROP. Pegasus has been released for its 30th flight.

0538 GMT (1:38 a.m. EDT)

T-minus 30 seconds. The batteries for the first stage flight control fins have been activated, allowing the fins to undergo a sweep test prior to launch. The fins are used to steer the rocket during its initial climb to space.

In the final moments prior to release of Pegasus, the L-1011 carrier aircraft crew will oversee the last seconds of the countdown and flip the switch that will drop the three-stage vehicle, with the HETE 2 spacecraft aboard, from the belly of the jet.

0537 GMT (1:37 a.m. EDT)

T-minus 1 minute and counting.

0536:50 GMT (1:36:50 a.m. EDT)

T-minus 90 seconds. The carrier aircraft now achieving the proper launch heading. The Pegasus will be released in a southeasterly direction with a flight azimuth of 118.5 degrees.

0536:20 GMT (1:36:20 a.m. EDT)

T-minus 2 minutes. Data charts are now recording.

0535:20 GMT (1:35:20 a.m. EDT)

T-minus 3 minutes. The transient power bus has gone internal and the rocket's guidance computer now in free inertial mode.

0534:20 GMT (1:34:20 a.m. EDT)

T-minus 4 minutes and counting. The launch team now entering the final checklist for today's flight of the Pegasus rocket with NASA's High Energy Transient Explorer 2 spacecraft.

0533:20 GMT (1:33:20 a.m. EDT)

T-minus 5 minutes and counting.

0532 GMT (1:32 a.m. EDT)

The Pegasus rocket's avionics have switched from power provided by the L-1011 to internal battery power with no problems reported.

0530 GMT (1:30 a.m. EDT)

The final launch readiness poll by NASA Launch Manager Ray Lugo has been performed and all systems remain "go" for drop the Pegasus rocket.

0530 GMT (1:30 a.m. EDT)

T-minus 8 minutes and counting. Weather conditions have been verified "go" for today's launch.

0529 GMT (1:29 a.m. EDT)

The pilot of the L-1011 Stargazer carrier jet reports the final turn to fine-tune the flight path on the proper heading now complete.

0528 GMT (1:28 a.m. EDT)

T-minus 10 minutes. Orbital Sciences' air-launched Pegasus rocket will be making its 30th flight today. The vehicle is currently riding a three-year stretch of 15 consecutive successful launches, placing 43 satellites into space. Ironically, the last Pegasus failure was on November 4, 1996 when the original HETE spacecraft was lost after the rocket malfunctioned and did not deploy the satellite.

0526 GMT (1:26 a.m. EDT)

Checks of the flight termination system has been completed without any problems noted. The FTS would be used to destroy the Pegasus rocket should a problem arise during the launch.

0525 GMT (1:25 a.m. EDT)

The rocket's flight termination system has gone to internal power.

0523 GMT (1:23 a.m. EDT)

T-minus 15 minutes and counting. The release mechanism that will drop the Pegasus rocket from the L-1011 carrier jet is now being armed. Also, the aircraft has made the second right-hand turn to head back towards the launch point.

0517 GMT (1:17 a.m. EDT)

And now the L-1011 is making a 90-degree right-hand turn as it loops back towards a southeasterly trajectory for the launch of the Pegasus rocket. This turn heads the plane in a northeasterly path before making another sweeping right-hand turn.

Officials report there will be a three-minute window of opportunity in which to release the rocket in the 20-mile long drop box today. If the drop cannot be accomplished during that time, the carrier aircraft could circle around and try one more attempt before having to scrub today's mission.

0514 GMT (1:14 a.m. EDT)

T-minus 24 minutes and counting. The carrier aircraft has passed by the planned drop point for the Pegasus rocket today at an altitude of about 39,000 feet. The flight crew reported smooth conditions, north-northwesterly winds at 18 knots and clear skies. The plane will continue on its current northwesterly heading for the next few minutes before looping around.

0508 GMT (1:08 a.m. EDT)

Now 30 minutes away from the scheduled drop time when the three-stage Orbital Sciences Pegasus rocket is released from L-1011 carrier aircraft above the Central Pacific Ocean in the Marshall Islands. Release is targeted to occur at 0538 GMT, which is 1:38 a.m. U.S. Eastern Daylight Time and 5:38 p.m. local time in Kwajalein where the mission originated.

In the past Capt. Bill Weaver has described what is like to fly the Stargazer jet during the launch of a Pegasus booster.

"When we drop the Pegasus, there is a pronounced jolt in the airplane. We can all feel it and hear this. The nose will pitch up...because of the 52,000 pound weight loss."

The actual release of Pegasus will be in the hands of the co-pilot sitting in the right-hand seat. He will flip a switch on the center console of the cockpit to drop the rocket.

"When the rocket motor ignites, it should be about 500 feet below the airplane, as that lights and accelerates beneath us, it sounds kind of like a freight train going by," Weaver said.

The plane will make a turn to the left to avoid flying through the exhaust plume from the solid-fueled rocket.

"As soon as we rollout from the turn, the Pegasus should be plainly visible in front of us and below us and then it goes up very steeply. Quite impressive and spectacular," Weaver said.

0504 GMT (1:04 a.m. EDT)

The Stargazer carrier aircraft has completed the 180-degree U-turn and is now headed northwesterly towards the drop box for today's launch. The plane will actually fly through the 20-mile-long, 4-mile-wide box before making another looping turn for roll onto the proper launch heading.

0458 GMT (12:58 a.m. EDT)

The L-1011 pilot reports the aircraft has passed through the peak climb point and is now making a sweeping U-turn to the right. The jet departed Kwajalein flying in a southeasterly direction. It will now head northwesterly through the drop box where the Pegasus rocket will be launched in about 40 minutes.

0453 GMT (12:53 a.m. EDT)

T-minus 45 minutes and counting. NASA Launch Manager Ray Lugo reports everything is proceeding normally with no problems to report with the HETE 2 spacecraft.

0445 GMT (12:45 a.m. EDT)

The flight path of the L-1011 today takes the jet southeasterly away from the Kwajalein Missile Range site. It will then make a U-turn to head northwesterly through the predetermined drop box where the Pegasus rocket is due to be released at 0538 GMT today, allowing the aircraft crew to verify weather conditions. The box extends 20 miles in length and four miles wide. Once another looping turn is made after passing through the box, the aircraft will fly southeastward on the proper heading for the launch at a flight azimuth of 118.5 degrees. This is scheduled to be the standard 58-minute flight of the L-1011 from takeoff until the rocket's drop. The drop point is about 60 miles southwest of the Kwajalein atoll.

0440 GMT (12:40 a.m. EDT)

T-minus 58 minutes and counting. The "Stargazer" carrier aircraft with the Pegasus rocket attached to its belly has departed Kwajalein Missile Range on an atoll in the Central Pacific Ocean for today's launch to place NASA's High Energy Transient Explorer 2 spacecraft into orbit to detect gamma ray bursts -- the most powerful explosions in the universe.

0437 GMT (12:37 a.m. EDT)

The ground launch team has been polled by Orbital Sciences Launch Conductor Mark Ferguson in preparation for the L-1011 carrier jet to depart Kwajalein. Takeoff time is set for 0440 GMT (12:40 a.m. EDT). And again the target launch time has been moved up to 0538 GMT (1:38 a.m. EDT) following a normal 58-minute flight of the L-1011.

0433 GMT (12:33 a.m. EDT)

The pre-takeoff poll of the NASA launch team by agency Launch Manager Ray Lugo was just performed with no problems reported. Also, the weather has been verified acceptable in the "drop box" where the air-launched Pegasus rocket will be released over the Central Pacific Ocean, which is about 4,200 miles west of the U.S. mainland and 2,100 miles west of Hawaii.

0425 GMT (12:25 a.m. EDT)

The L-1011 carrier aircraft, called "Stargazer", is now taxing from the Hot Pad staging zone to the runway at Kwajalein Missile Range for takeoff in the next few minutes. All activities continue to go well and launch officials have moved up the target drop time to 0538 GMT (1:38 a.m. EDT). The available launch window for today's attempt opens at 0535 GMT and extends about five hours.

0350 GMT (11:50 p.m. EDT)

The countdown is continuing for the launch of an Orbital Sciences Pegasus rocket today. Departure of the L-1011 carrier aircraft is about one hour away and launch of the Pegasus expected less than two hours from now.

At the Hot Pad staging area where the aircraft is parked at Kwajalein, the engines have been started on the L-1011, and workers are now powering on the Pegasus' flight termination safety destruct system and removing the Safe and Arm pins. Also, Range Safety is about to perform an interrogation link check with the rocket's C-band beacon used for tracking the vehicle during launch.

0130 GMT (9:30 p.m. EDT)

Launch operations are getting underway at this time for today's planned flight of the Orbital Sciences Pegasus rocket with NASA's High Energy Transient Explorer 2 spacecraft. Release of the air-launched rocket from the L-1011 carrier jet is targeted to occur at 0545 GMT (1:45 a.m. EDT).

The launch team will be reporting on station at the remote control center in Hangar AE of Cape Canaveral Air Force Station in Florida, nearly half-way around the world from the actual staging site for today's mission. The launch is being conducted from the Kwajalein Missile Range in the Central Pacific Ocean over 4,200 miles west of the U.S. West Coast.

Final pre-flight activities at Kwajalein are being performed by a crew of two-dozen personnel who traveled to the U.S. military facility known for testing ballistic missiles. Today's launch will be the first space flight to deliver a satellite into orbit from Kwajalein.

Clocks are counting down to departure of the "Stargazer" carrier aircraft from Kwajalein, bound for the preset launch zone over the Pacific Ocean. Takeoff is about 3 1/2 hours away, and the Launch Panel Operator will now board the jet at the Hot Pad staging area. The LPO will power up the Pegasus rocket under direction from the Launch Conductor.

While that chore is underway, efforts to close out the Pegasus' access compartments will be finished and Range Safety engineers are scheduled to verify that the Flight Termination System is functioning by sending arm and fire commands to the FTS antennas.

Later, other tests will be conducted to ensure the readiness of Pegasus systems. The checks will include verifying the rocket can switch from aircraft-supplied power to its own internal batteries, the Inertial Measurement Unit guidance computer, the Pegasus' flight computer and telemetry system are working normally and testing the control link from the LPO to the payload.

Activities will culminate with the team members opening their launch checklist and starting the carrier jet's engines in the final hour prior to takeoff. Also, the FTS will be powered on and all safety inhibits checked, the Safe and Arm safing pins removed and the rocket placed in a ready state. Shortly before departure, the L-1011 will taxi from the Hot Pad to the runway, scheduled for around 0425 GMT (12:25 a.m. EDT). Takeoff is planned for 0447 GMT (12:47 a.m. EDT).

SUNDAY, OCTOBER 8, 2000

The second attempt to launch NASA's High-Energy Transient Explorer 2 spacecraft aboard an Orbital Sciences Pegasus rocket is set for later tonight in a mission originating from the Kwajalein Missile Range located in the Central Pacific Ocean.

Countdown activities are due to begin at 0130 GMT (9:30 p.m. EDT), with release of the air-launched Pegasus from its carrier aircraft at 0545 GMT (1:45 a.m. EDT).

The launch had been scheduled for early Saturday morning but was postponed 48 hours due to a communications problem and a broken cable. NASA had announced the communications glitch was an outage between the remote launch control center at Cape Canaveral Air Force Station in Florida and Kwajalein. However, project officials said Saturday the problem was actually between the HETE 2 ground station in Kwajalein and the craft's Mission Operations Center at the Massachusetts Institute of Technology. MIT runs the HETE 2 mission for NASA.

Controllers use an Internet link to relay data from the Kwajalein station back to MIT. But there was a previously-unannounced Internet service outage Friday night to the Kwajalein Missile Range, HETE officials said.

In addition, a ground support cable was damaged Friday while workers were removing a protective cover over the Pegasus rocket's payload fairing.

SATURDAY, OCTOBER 7, 2000
0340 GMT (11:40 p.m. EDT)

Launch of the Orbital Sciences Pegasus rocket and NASA's High-Energy Transient Explorer 2 has been rescheduled to Monday at 0545 GMT (1:45 a.m. EDT) in a mission staged from the Kwajalein Missle Range located in the Marshall Islands of the Central Pacific Ocean.

The 48-hour delay was ordered due to a communications glitch between the launch control center at Cape Canaveral in Florida and a ground station for the HETE 2 spacecraft at Kwajalein. It is mandatory that the two sites be linked together for the launch. Workers also have to repair a broken cable in ground support equipment used in final pre-flight preparations for HETE 2.

The air-launched Pegasus rocket will be embarking on its 30th flight.

0220 GMT (10:20 p.m. EDT)

SCRUB! Today's planned launch of an Orbital Sciences Pegasus rocket carrying NASA's HETE 2 spacecraft has been scrubbed. Details are still sketchy on the cause of the postponement. A new launch date has not been announced. We will post further details on this page as soon as they are available.

FRIDAY, OCTOBER 6, 2000

An air-launched Pegasus rocket is ready to boost a NASA probe into space at 0545 GMT (1:45 a.m. EDT) on Saturday that will detect the most powerful explosions in the universe. Known as the High-Energy Transient Explorer 2, the tiny craft seeks to detect mysterious gamma ray bursts.

The Orbital Sciences-built rocket will soar to orbit once released from its L-1011 carrier aircraft about 40,000 feet above the Central Pacific Ocean. The mission is being staged at the Kwajalein Missile Range in the Marshall Islands.

One week ago today the Pegasus left its home facilities at Vandenberg Air Force Base in California for the two-day ferried by the L-1011 to Kwajalein. After arriving the small team of two dozen rocket, satellite and aircraft personnel have performed several routine tests in advance of Saturday's launch.

A comprehensive Combined Systems Test to verify the connections between the HETE 2 spacecraft, its launch vehicle and the L-1011 was performed on Monday. The test was actually run at Vandenberg but was repeated in Kwajalein because parts of the Pegasus steering system were temporarily removed for the ferry flight and then reinstalled after arrival. On Tuesday a data flow demonstration test and end-to-end check of HETE 2 with its ground station network were performed. The mission dress rehearsal followed on Wednesday with teams not only in Kwajalein but half-a-world-away at the launch control center in Cape Canaveral, Florida, participating.

Activities will get underway Saturday at 0130 GMT (9:30 p.m. EDT tonight) when the launch team opens their checklist, kicking off the final procedures to ready the L-1011, Pegasus and HETE 2. Once the checklist is opened, the day's available launch window will be constrained to five hours in duration. Taxi of the jet from the "hotpad" staging area to the runway is expected around 0425 GMT (12:25 a.m. EDT), with takeoff at 0447 GMT (12:47 a.m. EDT).

The carrier aircraft will fly to a point about 60 miles southwest of the Kwajalein atoll to release Pegasus for its 11-minute climb to orbit.

Weather forecasters are predicting generally acceptable conditions.

Spaceflight Now will provide continuous live updates on this page beginning at 0430 GMT (12:30 a.m. EDT).

You can read our preview story for more on the launch and a look at HETE 2's science objectives.